Serps rank different from each login location

[bakergraphix_yahoo.com]

I prepared a report yesterday morning and I had a variety of keywords ranking at #5. Today when checked from another location they are all over the place.

kitchen mats has been 11-15 for months, and then when checking from a school computer that starts a new session upon each login

Yesterday it was #5 as was anti fatigue mats - it has been 27-32.

Is google pulling in local hits and shifting the serp rankings?

the site is www.wellnessmats.com

any there suggestions would be greatly appreciated.

I know we have had duplicate content issues, and now reading some of the posts - perhaps "key word cannibalization"?

thanks

[bakergraphix_yahoo.com]

do you mean clearing the cache and history, each and every time you check?

obviously, i love the seomoz toolkit, but with numbers run only wed - they are usually not even close.

i did have some friends check it, and it closer the to numbers i had yesterday (on the front page - which of course is every clients battle cry - they don't want to hear about conversions).

thanks -

[ResslerMotors]

I like that approach!

[danbocain]

Pretty accurate response by Ressler.  I use SEOmoz PRO Campaign Rank check, SEOBook's Rank Checker, and Market Samurai's rank checker. I then load the data into 3 sheets on a Spreadsheet and get the averages dynamically calculated onto a 4th spreadsheet so the client can see an estimated position ranking from 3 data sources.

[ResslerMotors]

I check my rankings three different ways.

1. Dedicated browser that I only use to search.  I reset all the data every time I use it, and I never click on anything.  If things seem out of sort I will reinstall it.
2. SEOmoz.  I use their ranking checker in the Pro tools
3. SEOBooks Rank Checker.

By using three different options I'm able to see exactly where I'm linking.  In the off chance that I still think its off I will ask a couple of friends to search it.

That being said, location does have an affect on rankings.  Google wants to find the most relevant item for you, and location can be a determining point if everything else is equal.